Siloxane-modified networks, surface

Surface Analysis of Siloxane Modified Networks ESCA... 

Siloxane containing interpenetrating networks (IPN) have also been synthesized and some properties were reported 59,354 356>. However, they have not received much attention. Preparation and characterization of IPNs based on PDMS-polystyrene 354), PDMS-poly(methyl methacrylate) 354), polysiloxane-epoxy systems 355) and PDMS-polyurethane 356) were described. These materials all displayed two-phase morphologies, but only minor improvements were obtained over the physical and mechanical properties of the parent materials. This may be due to the difficulties encountered in controlling the structure and morphology of these IPN systems. Siloxane modified polyamide, polyester, polyolefin and various polyurethane based IPN materials are commercially available 59). Incorporation of siloxanes into these systems was reported to increase the hydrolytic stability, surface release, electrical properties of the base polymers and also to reduce the surface wear and friction due to the lubricating action of PDMS chains 59). 

As will be discussed, incorporation of siloxane oligomers modified the elastic moduli and the fracture properties of the crosslinked epoxy network. Previous work 15) indicated that the surface of these materials was rich in siloxane, which is believed to foster a low energy surface. These characteristic properties have led to our interest in the friction and wear of siloxane-modified epoxies. 

The sol-gel synthetic technique is used to fabricate a porous structure composed of transition metal aUcoxides. These structures most commonly utilize a siloxane (Si O) to form the backbone structure. The synthesis of these sol-gels involves a hydrolysis of a silicone monomer followed by the condensation of the silica into a porous structure with a three-dimensional networked structure. The physical structures of these sol-gels can be tailored to produce structures with a wide range of useful properties and the chemical surface chemistry can be modified to produce various surface interactions. 

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